Control Design

Technology enables OEM access to its machines and the benefits that come with it

The Industrial Internet of Things (IIoT) will significantly change the world, predicted Greg Gorbach, vice president, ARC Advisory Group. While his prediction isn't exactly bold or risky, Gorbach and a group of roundtable presenters at ARC Forum 2015 in Orlando, Florida, discussed how IIoT not only will change industry, but often how it's already had an impact.
"What is an Industrial Internet of Things thing?" asked Gorbach. "It's an industrial asset, but it's also a platform for new applications and services. It's part of an econsystem, but it has to be secure."
While reduced machine or asset downtime and more rapid service response are the top two drivers, according to ARC survey results, IIoT also can improve operating performance,…

Should you design I/O systems based on the user's needs or the application's

Enclosureless I/O systems have been available for years, but new installations often still use traditional enclosure-based strategies. This happens despite the fact that a centralized enclosure approach has several downsides. What are some of the…

Reduce Cabinet Space and Wiring

Machine mount — the placing of everything from I/O to PCs directly on factory floor equipment instead of in a cabinet — is increasingly being used. The benefits are less cabinet space and wiring, as well as reduced commissioning time and…

Many end users don't really know what PAC is, or what the differences between PLCs and PACs are. The reality is, OEMs and machine designers need to educate users better.

If asked, "Is there really any difference between programmable logic controllers (PLCs) and programmable automation controllers (PACs)," the machine end user will likely answer, "No."
Or that person might ask, "What is a PAC?" You may even get a few…

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Many end users don't really know what PAC is, or what the differences between PLCs and PACs are. The reality is, OEMs and machine designers need to educate users better.

If asked, "Is there really any difference between programmable logic controllers (PLCs) and programmable automation controllers (PACs)," the machine end user will likely answer, "No."
Or that person might ask, "What is a PAC?" You may even get a few…

Recent

New Designs Also Allow Use Outside the Control Cabinet

Industrial devices that have intelligence are a hot topic, and power supplies are no exception. According to Mike Garrick, marketing manager for power supplies at Phoenix Contact USA, users expect the capability to network devices that never had…

Current Approaches Automate Automation

Increasing demands on the time and resources of today's engineers mean that modern control software should be designed with efficiency in mind. "Trends in the industry lean toward the ability to automate the automation software, providing engineers the tools to programmatically change the software configuration of a machine, including the actual PLC code. This enables an OEM to automatically configure the machine controller's code to match the machine's actual I/O layout or to modify the software configuration based on the company's orderable machine options, without requiring the efforts of a controls engineer," says Daymon Thompson, TwinCAT product specialist, Beckhoff Automation.
The resulting better use of engineers' time boosts their…

Recent

Current Approaches Automate Automation

Increasing demands on the time and resources of today's engineers mean that modern control software should be designed with efficiency in mind. "Trends in the industry lean toward the ability to automate the automation software, providing engineers the tools to programmatically change the software configuration of a machine, including the actual PLC code. This enables an OEM to automatically configure the machine controller's code to match the machine's actual I/O layout or to modify the software configuration based on the company's orderable machine options, without requiring the efforts of a controls engineer," says Daymon Thompson, TwinCAT product specialist, Beckhoff Automation.
The resulting better use of engineers' time boosts their…

New technologies make it easier to program and integrate FPGAs into your control systems

If you have an application requiring very high-speed control, signal processing or both, then an FPGA may be a better alternative than trying to push a conventional control system architecture too far and too fast. In the past, you'd be faced with…

Researchers Will Demonstrate Feasibility of Using Standardized 3D Models for Electronically Exchanging and Processing Product and Manufacturing Information

National Institute of Standards and Technology (NIST) researchers and their industrial partners have embarked on a Design to Manufacturing and Inspection Project to add a new dimension to manufacturing capabilities. They will demonstrate the feasibility—and benchmark the advantages—of using standardized, 3D models for electronically exchanging and processing product and manufacturing information all the way from design through inspection of the final part, a tightly integrated, seamless string of activities that manufacturers are calling a "digital thread.”
Tom Hedburg, one of the researchers in the project, explains, “What we’re talking about is a 3D drawing with all the product information embedded in it. It’s a way of…

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The winter 2015 rankings of the best product and machine design software published by G2 Crowd is here.

The first Grid report for product and machine design software, published by business software review site G2 Crowd, ranks seven products to help purchasers in their selections.
The Winter 2015 report is based on more than 170 reviews written by business and engineering professionals.
The Grid, which is created from G2 Crowd's software review platform, factors in customer satisfaction reported by users and vendor market presence determined from social and public data to rank products.
Product and machine design software is a subcategory of computer-aided design (CAD) software, targeted specifically toward designers and engineers across a number of disciplines, including manufacturing, product design, automotive, and aerospace. These tools…

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Applied Motion Products launches its first Motion Control Design & Innovation Competition. First place prize is $5,000.

Applied Motion Products launches its first Motion Control Design & Innovation Competition. The competition is open to teams of young engineers primarily university and high school students, robotics and motion control clubs.
Using a $1,000…

Power Transmission Applications Use Lead Screws and Timing Belts, While Motion Control Applications Include High-Precision, Highly Repeatable Systems Equipped With Feedback and Servo Loops

Recall that a main component of a linear motion system is the linear actuator, which can be a pneumatic, hydraulic or electrical device. A good way to think of the various technologies in terms of a particular task is in the application's…

Power Transmission Applications Use Lead Screws and Timing Belts, While Motion Control Applications Include High-Precision, Highly Repeatable Systems Equipped With Feedback and Servo Loops

Recall that a main component of a linear motion system is the linear actuator, which can be a pneumatic, hydraulic or electrical device. A good way to think of the various technologies in terms of a particular task is in the application's…

Recent

Stepper Motors Also Are Simpler to Deal With During the Design Phase of a Project.

Selecting the right stepper motor—or any stepper motor at all—comes down to answering some questions about what's to be moved, how fast to move it and with what precision. After that, other factors such as cost and suitability to a given…

Evolved from exotic add-ons with separate controls to regular-guy devices serving alongside other mainstream machine components using common controls, robots are well-integrated and ready to cooperate

Robots used to be a big deal. Forests of huge yellow, orange and white arms juggled and welded car bodies, and everyone else looked on in awe at their amazing moves and equally huge price tags.
Times have changed, and many robots appear to be…

See the Latest Product Innovations in the Industry

Display of PressureAG200 media-isolated, digital pressure gauge has 4–20 mA output signal and large LCD that can display psi, bar, kg/cm, ATM, inches H20 and Hg measuring units. With a test button, users can evaluate loop current to ensure the system is set up correctly and adjust the current in 2 mA increments. Loop current update rate is 32 times/s; the display updates 3 times/s. American Sensor Technologies973/448-1901www.astsensors.com
Valve DriverD1 PWM Valve Driver is designed to drive and manage proportional valves. It converts proportional command voltage to a -1.1…1.1 A signal to drive the valve’s linear force motor. It works with 12 or 24 Vdc power supply and valve deadband; dither amplitude and maximum current are…

Applied Motion Products launches its first Motion Control Design & Innovation Competition. First place prize is $5,000.

Applied Motion Products launches its first Motion Control Design & Innovation Competition. The competition is open to teams of young engineers primarily university and high school students, robotics and motion control clubs.
Using a $1,000…

How to make sense of the many options available for ensuring accuracy

Our metal stamping machines need to be able to run a variety of parts through the press. Any errors in the coil-change process can be costly. The manual changeover itself is time-consuming, but a damaged press means expensive repairs and lost…

Today's Robots Have 20/20 Vision

Machine vision systems have long played an important role in inspecting, identifying and guiding parts. Current systems provide an increasingly sophisticated integration of machine vision and robotics, boosting the number of automation options that…

Improvements in machine safety have come about due to changes in attitudes and technology

Machine safety has improved exponentially over the past few decades. Automation and technology have played a key role in improving, but there's still work to be done. In December 2014, we conducted an electronic survey to identify usage and…

Proximity Sensors Enable Object Detection to Determine What is Where

To be sure you hit a target, you have to see or somehow sense it. That truth lies behind the theory and practice of presence sensors, which are used to determine whether a box, bottle, piece of metal, or something else is there or not. Armed with…

Would Our Future Workers be Robots or Humans?

What will the next generation of manufacturing workers look like? One thing is certain. These individuals will be able to work with robots — capable of programming them, as well as allowed to interact with them, side by side.
Ntxuzone Yang and…

The safety of your industrial networks is no joke. Are you doing enough to protect your plant, machines and processes from cyber attacks?

With all the latest security breaches and hackers breaking down firewalls to steal information as if hacking was an accepted and recognized global sport, industry leaders are rethinking the safety of their industrial networks.
There's nothing fun…

The upsides and downsides of controller-display combo units.

A combo controller and operator interface can save big compared to separates.
As the miniaturization of electronics continues its relentless march across the personal-consumer-device landscape, it's only natural for it to proceed apace in machine…

Because they've gotten smarter and have additional capabilities, panel meters now can take over some functions previously handled by PLCs. For instance, a panel meter with math capabilities can keep count and shut off a machine after a fixed number…

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The latest report examines a range of topics from the industrialization of the Internet of Things (IoT), to the growth impact of the maker movement.

For over 30 years National Instruments has been monitoring trends across the industry that help engineers and scientists work in an productive environment. The company does this by informing their users of efficient systems that can accelerate productivity, innovation, and discovery.
In 2014, National Instruments published its first NI Trend Watch and they have just releases the 2015 edition.
According to the industry leader, the latest report examines a range of topics from the industrialization of the Internet of Things (IoT), to the growth impact of the maker movement.
" know that future systems will be based on architectures and technologies that may not even exist yet," said Eric Starkloff, NI executive vice president of global sales…

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If a Wireless Industrial Device Needs to Connect to Send a Process Update or Alarm and Can't Though the Signal Appears Strong, the Consequences Could be Severe

Have you ever been on a public Wi-Fi hotspot such as a coffee shop or airport with the signal strength indicator on your mobile device or laptop indicating a nice strong signal but then not being able to log on the network? The likely reason is that…

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No Matter What Type of Switch is Used, It’s Important to Recognize and Account for the Needs of Engineering Staff, Maintenance Personnel and Operators to Access a Machine for Upkeep and Cleaning.

When you've got to stop, you've got to stop. For machine builders, that's usually a job for safety switches. They allow safe access to dangerous machines by putting systems in a harmless state, which could mean cutting off power completely. In selecting a safety switch, it's important to keep in mind frequency and function, according to Roberta Nelson Shea, global marketing manager for Rockwell Automation. For something that needs to be opened only once a year, the best solution likely is to use simple guards, such as by completely encasing the area. More frequent access has to be easier. It's when access is frequent, but not constant that an interlocking safety switch comes into play."You expect somebody needs to get in there at least…

Motion Control Revealed

Factory Automation: There are several levels of sophistication in industrial motion control, some simple, some less so. From NC Controls to Multi-axis Algorithms and PC-Based Computations, We've Come a Long Way.

There are several levels of sophistication in motion control, some simple, some less so.

At its most basic level, one button starts a motor and another button stops it. The velocity of the movement is fixed by the motor's characteristics, e.g., an induction motor with a rated RPM and line frequency. Functionally, there is no position or velocity defined. Applications that fit these criteria might include motors powering conveyer belts, pumps, fans, and everyday devices found in homes such as furnaces, washing machines, dryers, or vacuum cleaners.

Many industrial applications control motion this way as well. The start-button's signal may be processed by a PLC or controlled by additional devices such as sensing switches, which may replace or augment the start or stop buttons.

More precise motion performance controls trajectory and velocity over time and specifies endpoints or distance to be traveled. In addition, two or more axes may execute simultaneously to create a composite move through space. A motor drive generates various excitation signals, phases, and frequencies that direct motors to run at variable speeds in either forward or reverse, as well as remain stationary.

Precision Motion Principles

This article covers the principles and execution mechanisms of precise motion control. A thorough review of these principles may permit readers a chance to better understand the high-level programming capabilities of current motion control technologies and apply them practically, i.e., collecting motion commands, graphically describing trajectories (defining the cutting paths from raw stock to finished part), or programming a robot, to name just a few.

This article also describes how a PC may be used to precisely control motion over several axes. In this case, the actuators may be independent single axes, three-linear-axes systems typically found on milling machines, or sophisticated five-axes systems found controlling robots with articulating or jointed arms.

The control algorithm defines the move of each axis as a function of time and then computes the trajectory in increments of time or [Delta]t. In accordance with a sensible division of computing labor, only a few, simple motion controllers close some of the above-mentioned low-level loops in the PC, while most other motion controllers handle the loop closures and low-level routine computations of one or more axes with separate axis CPUs.

It's All About Feedback

The feedback loop is a key element of precise motion control and has to be in place before any motion commands can be executed. Figure 1 shows a feedback loop including a digital rotary encoder that provides two pulse trains, normally identified as track A and track B. These encoders provide 4,096 pulses per turn and track; so by decoding every transition, 16,384 pulses are obtained per revolution. The two tracks are resolved in a bi-directional logic, and feedback pulses are applied to an up/down counter. The contents of the counter may be applied to a digital-to-analog (D/A) converter and the resulting analog voltage serves as a signal to the drive that generates the motor excitation. In most cases, the encoder is directly and physically coupled to the motor shaft.

Figure 1: The Feedback Loop is Key

If the polarity of the feedback pulses is correct, the counter initially reset, and zero analog voltage defined as no motion, then this system of feedback will hold the motor at a standstill. Any disturbance that tries to rotate the shaft will cause an offset in the counter and thus a corrective drive signal to oppose the action. A conventional tachometer coupled to the motor's shaft could be introduced at this point to enhance the feedback system and stabilize the velocity loop, again, as long as it observes the proper polarity of the signal.

Numerical Control's Legacy

Today's sophisticated motion controls had their origin in the hardware Numerical Control(NC)Systems of the mid-1960s. In addition to the feedback loop shown in Figure 1, NC systems provided coordinated command pulse trains to the feedback loop of each axis. Each up/down counter had two more inputs: Command pulse train and sign. When command pulses were added to the counter (+ pulses), the value in the counter increased and caused a drive signal to the motor in a way that generated feedback pulses (- pulses) that subtracted from the counter again. During the move, the offset value in the counter was the following error. When command pulses ceased, the counter eventually returned to a zero value and the move stopped.

Figure 2 shows the introduction of the command pulse train. An anti-coincidence circuit assures that no pulse is lost from either source. If for example, a command (+) and a feedback (-) occur together, no count pulse is passed on to the counter. If a command (+) and a feedback (+) should occur together then the counter is incrementally advanced by two.

Figure 2: Get on the Pulse Train

Early NC systems used rate multipliers to generate pulse trains for the individual axis. Basically, a common counter chain divided a high-speed pulse source by several decades; each axis gated-out the proper number of pulses according to its programmed command. The commands for each axis were given in incremental form; as such, the value was equal to the number of pulses to be generated per move block.

Since axes data are gated from the same common divider chain, a simultaneous move results. If the high-speed pulse source changes its frequency over time, then all axes will follow in lock step, allowing for acceleration and deceleration or feed-rate override without sacrificing the programmed path. Figure 3 shows an example of a counter chain with boxes representing the gates, selected with the individual incremental axis data.